Fixed small bag on xml code.

Replaced `euro` whit `#8364` euro html code in order_report table xml.

NOTE: could it be necessary to do the same for any other `euro` statement in html/xml ?
Fixed small bag on xml code (2).

Replaced `euro` whit `#8364` euro html code where it was necessary.
Moved gas_details data from the formset_class to the context.

Moved gas_details data from the formset_class to the context, in order to make the template do the rendering work.
GF DB backup guide.

- wrote bash script to:
    1. create a META file which contains the last GF commit (hash) and current date
    2. dump GF DB basing on settings.py information
    3. put META and dump files into a tar.gz which is rotated to keep an history of backups
- wrote a backup guide which explains how to restore GF DB to a previous version, assuming to have the tar.gz file introduced above.